2nd Gen Non-Engine/Transmission ? about fuel milage

[SharpMotors]

just got back from a short road trip and my fuel milage is not to good. i was towing a 18 foot enclosed car trailer total weight of trailer and stuff inside was no more than 6000lbs. the truck is a 99 3500 4x4 quad cab with a edge drag comp box (that was turned off) dd3 injectors ,4 inch straight pipe,fass fuel system,afe stage 2 air box,complete dtt trans with 90% convertor,4. 10 gears,and the tire size is 255-85-16. before i left i changed the oil ,cleaned the air filter,and installed a new fuel filter. anyways at a average speed of 70 on flat ground i only was getting 10 miles to the gallon. this numder is not what the dumb over head console said this was me dividing # of gallons by miles i went. what is the deal

 

[sewman]

Well I think w/winter fuel & doing 70 you aren't to far off?I just got 12. 5 w/my 98 12v pulling 4,000lb.

Did your truck come w/265's?

Bob

 

[WestTN]

Aerodynamics play a large part in fuel mileage. I can tow my 6x10 single axle closed utility trailer and only get about 1 mpg better than pulling my 29' dual axle travel trailer at the same speed. The weight is only a minor factor. It all depends on how the air flows around the truck and trailer combo. When hitched, does your trailer set level with the road? If not, this one might surprise you with the difference leveling it could make.

 

[BTighe]

i guess ill stop crying about 14-15mpg with my 6x12 enclosed tandem. it weighs about 4000 most of the time. i was told a v-nose would do better.

 

[FourBarR]

i have a 98. 5 qc lb 2 wd. weighs 6500lbs. with me and full fuel. towing 6x10 enclosed inter state 3000lbs. using metric converter to change kilometers to miles and liters to imperial gallons . mileage is consistantly 21to 23 in winter. only mods are kn and 4 in. ss exhaust . also its an auto.

 

[SharpMotors]

i have checked my fuel milage before without the trailer and i will average 12 to 12. 5. maybe im wrong but i thought i would be better

 

[sewman]

The mpg I was talking about was with a 6x12 tamden enclosed flat front

I also have a 16' v-nose that got 15. 5 in the summer w/6,000 lbs

Speed will make a big difference too.

Bob

 

[pwknapp]

Just wondering if you compensated for the tire size difference from stock. My odometer in my 96 with 255/85's is off 8. 4-8. 8 percent. When I ran hot shot, mileage was directly proportionate to wind resistance. I checked it every tank for over 425k.

 

[bmoeller]

pwknapp-



What kind of mileage do you see with your truck (empty)? Do you have 4. 10s also? Did the 255s improve or worsen the mileage any?

 

[RonaldLarson]

Tires

My '99 came with 245/75/16's. I went to 265/75/16's and the difference was 9. 9 %. Verified by GPS. This is likely your dilema.

Ron

 

[SharpMotors]

that is a good point but yes i did compensate for tire size i have checked it many times and with the speedo reading 65 i am realy going 72 ish.

 

[CMckee]

i hauled a 35' fifth wheel this summer weighing in just under 10,000lbs, averaged 70 mph got 18mpg. usually get 36 without trailer.

 

[DennyDay]

Fuel Quality - - or lack of!

I think most will find a combination of problems, the first being winter fuel and second poor quality or low centane rating. My overall mileage is 15 mpg, been getting 19 mpg.



Incidently, checked TA fuel prices just now, and except for several NY locations, West Virginia is the highest at $2. 199/gallon.



Denny

 

[SharpMotors]

well i will have to see what is going on with my truck i would really like to see 17 to 18 mpg. would adding a bottle of cetane boost or something like that help

 

[pwknapp]

bmoeller, last tank on winter fuel I got 13. 4 mpg with some idle time. (it was 15-20 below). Tank before was 15. 2 mpg with minimum idling. Usually average 16. 5 mpg with the 255/85's, with 235/85's I averaged 13. 4 mpg for years. I think the 255's effectively give me about a 3. 80 gear ratio. Next set of tires I may try the 35/10. 50/16's and see what they do for mileage and ratio.



bigbad9r, the only time I saw 17-18mpg on the highway was running with some big trucks breaking the wind, got 21. 5 mpg following 3 trucks from Indy to Memphis running 85+/-.

 

[GAmes]

i hauled a 35' fifth wheel this summer weighing in just under 10,000lbs, averaged 70 mph got 18mpg. usually get 36 without trailer.

Here is where every one who pulls trailers and knows how to calculate mpg does their best Jim Bilushi_Animal House sneeze. Bulls***!!!!

 

[bmoeller]

Must be that "new math" they are teaching schools.

 

[bmoeller]

bmoeller, last tank on winter fuel I got 13. 4 mpg with some idle time. (it was 15-20 below). Tank before was 15. 2 mpg with minimum idling. Usually average 16. 5 mpg with the 255/85's, with 235/85's I averaged 13. 4 mpg for years. I think the 255's effectively give me about a 3. 80 gear ratio. Next set of tires I may try the 35/10. 50/16's and see what they do for mileage and ratio.

You have to run spacers in between the duals, I presume? Or did you get the newer rims for a later second gen truck? I can't even get my hand in between my duals, with stock size tires. Any clearance issues up front (steering-wise) with the 255's without a body lift?



I'm thinking of getting 235's or 255's the next go 'round. I don't tow a lot, and with 4. 10's, it'd be nice to drop the RPMs on the interstate, and hopefiully get a tad bit better mileage. Been hard to fill the truck, with the flatbed, to get a consistant mileage check. Was getting up to 17. 5mpg (summer) with the box on. Seems to have dropped to 15mpg, now(summer). 13. 25mpg @75mph w/winter fuel, all highway with virtually no idle time. Never got under 14 before, empty.

 

[pwknapp]

No spacers but (4) 02 rims and can't even think about putting on the rear chains. Added the D25 springs up front and zero clearance issues. Contemplating 1. 5" or 2" spacers for the 35/10. 50's. I'd definitely jump to the 255's if you don't need the 10 ply E load rating.

 

[SharpMotors]

i did swap out my rims for a set off of a 2001 no problems with tire rubing in the rear no problems up front but i do have a leveling kit